This invention relates to smoking articles having reduced free burn time including cigarettes, cigars and little cigars, herein generally referred to as cigarettes. By "free burn time" we are referring to the time it will take a cigarette to extinguish itself in the open air, free from contact between the burning cigarette and other surfaces while it is not being puffed. In a conventional cigarette this time could be the time required for a cigarette to burn from the point when it is first lighted until the point when substantially all of the tobacco has been consumed. In accordance with the present invention, the free burn time of a cigarette is reduced by the addition of one or more bands along the length of the cigarette which, unless the cigarette is being puffed on, causes the burning cigarette to extinguish before all of the tobacco is consumed. The material used in the bands has not heretofore been suggested for this purpose and is fully described herein.
For many years attempts have been made to design a cigarette with a reduced free burn time. Unfortunately none of these attempts have resulted in a cigarette having a reduced free burn time which would be acceptable to the consumer. In the past, attempts to develop a cigarette having a reduced free burn time have involved experimenting with one or more of the factors which affect a cigarette's rate of burning. U.S. Pat. Nos. 1,996,002; 2,013,508 and 1,999,222 describe cigarettes of decreased inflammability which will go out when not being puffed. The cigarettes do not extinguish themselves when being actively puffed. The bands described in U.S. Pat. No. 1,996,002 are from 0.25-0.75 inches in width and contain materials such as ammonium sulfate, ammonium chloride, ammonium phosphate, boric acid, sodium silicate, cellulose organic esters, cellulose ethers, natural resins, oleo-resins, synthetic resins, and phenolaldehyde resins.
U.S. Pat. No. 2,013,508 discloses the concept of applying a fire retardant material in a 0.25 to 0.75 inch band-like pattern to either the finished cigarette or to the paper used in forming the cigarette. The fire retardant employed is a cellulosic composition containing barium sulphide which is immersed in a film of zinc sulphide solution and attached to the cigarette with an agglutinating substance.
U.S. Pat. No. 1,999,222 discloses a plurality of strips of paper which are secured to the inner surface of the cigarette paper and coated with a suitable agglutinating substance. These strips are about one-sixteenth inch wide and the bands function to exclude the oxygen from the inner surface of the cigarette envelope so that the cigarette extinguishes if not being puffed on when the burning cone is in the banded region.
A different approach is described in U.S. Pat. Nos. 4,044,778 and 4,187,862 wherein the wrapper which encloses the tobacco is coated with material deposited from an aqueous solution of an alkali metal silicate.
Other researchers have also described cigarette papers chemically treated to reduce the free burn time of the cigarette. Another suggested method of making cigarettes having a reduced free burn time was to incorporate fire resistant bands or rings into the cigarette itself which when reached would cause the cigarette to go out, even when being actively puffed. Chemicals have also been introduced into the tobacco to reduce the rate of burning. These attempts to create a cigarette with a reduced free burn time have introduced toxic substances, increased smoke yields or resulted in perceptible changes in the flavor impression of the cigarette or produced a cigarette which would extinguish while it is being smoked. In the past none of these efforts have been successful in producing a cigarette having a reduced free burn time, which would be acceptable to the average smoker.
When compounds are added, either to the tobacco or to the cigarette paper, it is likely that some fraction of the added material, its thermal decomposition products, or the reactants of its thermal decomposition products and tobacco moieties will enter the smokestream and be inhaled by the smoker. The prior art on cigarettes having reduced free burn times contains references to such materials as halogenated compounds, antimony trioxide, urea, diethanolamine, melamine, organophosphorous compounds, and the like, as materials for imparting flame resistance. The toxicity of some of these materials has been demonstrated. In addition the toxicity for many other suggested compounds is unknown. An added problem is posed by the fact that many of the solutions suggested by the prior art would decrease the efficiency of the tobacco burning process which is also undesirable.
In addition to the aforesaid considerations, there are important consumer preference problems which must be considered. Smokers expect that a cigarette will burn at a uniform rate. If the rate of burning slows and the cigarette extinguishes itself during normal use, the consumer is likely to conclude that the product is somehow defective, particularly because relighting a cigarette produces a highly undesirable taste. Similarly, in the past it has been found that modifications in the cigarette which reduce free burn time perceptibly alter the taste of the cigarette or increase the smoke yield or tar yield. Such characteristics would not be preferred by today's consumers.